The different grade of PET resin

Different grades of resins are appropriate
for different end uses. Their specific qualities make them ideal for the
product that they have been designed to package. What qualities of PET
are important depends very much on the product for which the bottles are
designed.

Carbonated soft drinks (CSD)

Strength: The resins in PET
bottles for carbonated soft drinks need very specific qualities. First
of all the material must be strong enough to withstand the internal pressures
of CO2 without distortion or expansion. It is determined to choose a resin
with high I.V. and low copolymer.

Clarity

In consideration of costumer's acceptance, a low
level of crystallisation is needed to achieve clarity in drink containers.
It is achieved by using a resin that has a low copolymer levels to add clarity
and reduce the crystallization.

Color

Although it is so important to achieve a perfect
clarity as mentioned above, with soft drinks, this property is not essential
because many soft drinks themselves are colored. In that case, the clear
soft drinks can also be packaged in the colored PET
bottle.

Water

Sometimes the container for carbonated drinks can
also be used for still water, however, some varies are still there.

Strength

Unlike carbonated drinks, the bottle filled with
still water only needs enough strength to hold water and to stand against
impact outside. The 0 .74~0.76 I.V. is enough in most cases.

Clarity

Since clarity is one of the most important reasons
why PET is used for water container, PET used in water bottles needs to
be very clear and maybe even with a slight tint of blue. A resin with higher
levels of copolymer adds to the clarity.

Purity

Because water is bland, having a container that
keeps tasteless and odorless is imperative. Usually PET doesn't affect the
taste of the product it protects. Therefore it becomes the key material
for water package.

Juice -- hot fill drinks

Juices and many other drinks like tea, dairy and
sport drinks or other high acid drinks are hot filled and hot pasteurized
afterwards. In such cases, PET is not the right choice, as PET bottles will
soften when containing water at 80 ? . With a hot fill temperature of 95
? , PP is becoming popular in the hot fill arena, but its clarity is not
comparable to that of PET. Consequently, the most common solution is mix
other materials like 25% PEN into PET to increase its hot fill temperature.
Alternatively, the crystallized PET neck could withstand a higher hot fill
temperature. In conclusion, PET resins with a higher temperature
and a faster rate of crystallization are preferred.

Strength and color & clarity

The factors of strength and color are not as important
to juices as to CSD or water while the purity factor is important, as juices
would be tainted by the taste of the plastic bottle that is not pure enough.

Beer

Beer is often regarded as an extension of the CSD
market, however, it also requires hot fill and barrier qualities, as PET
bottle allows oxygen to migrate in and carbon dioxide out, therefore
oxygen will oxidize the beer composition, changing the taste of the beer
and the way of overcoming this problem is resin barrier or coating barrier.
Because the technologies used to make beer bottles are varied and the applications
differ (cold filled or pasteurised), it is difficult to find a common trait.
Making a bottle to meet the desired requirements has been the most important
thing. The types of PET beer bottles typically used are: non-tunnel pasteurised,
one-way tunnel pasteurised and returnable/refillable bottles.

Barrier

Compared to PET used in CSD package, beer needs
higher performance in both CO2 and O2 barriers. The level required depends
on the type of beer, container size, distribution channels and environmental
conditions (storage time, temperature and humidity levels). Improvements
in barrier properties can be obtained via adding barrier coatings, creating
mutli-layer bottles and scavengers.

Color, clarity and UV protection

Further than the barrier properties, most beers
also need to be sheltered from UV (Ultraviolet) light. It can be obtained
via colorants or UV additives added to the PET
at the injection stage. Due to varied requirements for beer, resins that
provide an adequate barrier, UV protection and clarity must be chosen.

Strength

Beer bottles do need strength to endure the CO2
pressure. I.V. between the 0.80~0 .84 are favorable choice. Due to its lightweight,
not only the consumer benefit, also the transportation costs and energy
consumption in delivery are decreased. Because PET
bottles are so much lighter than alternatives, a truck can carry 60%
more of the beverage and fuel saving of 40% and less air pollution.